1. Technical Field
The present inventive concept relates to a highly integrated programmable non-volatile memory and a manufacturing method thereof, and more particularly to a memory device including an antifuse and a diode, or a variable resistor and a diode, an operation method thereof, and a manufacturing method of a plurality of memory cells capable of increasing the integration density by utilizing a vertical space.
2. Description of the Related Art
As a conventional technology, Korean Patent Registration No. 0904771 relates to a three-dimensional integrated circuit structure and a manufacturing method thereof, and discloses a three-dimensional IC structure including a single crystalline semiconductor layer having a plurality of devices, one or more insulating layers in contact with the top and bottom of the single crystalline semiconductor layer, and wiring and connection lines provided in the insulating layers, the wiring and connection lines directly or indirectly connecting the plurality of devices.
Also, as a conventional technology, Korean Patent Publication No. 1997-0067848 relates to a semiconductor memory device and a manufacturing method thereof, and discloses a semiconductor memory device including an access transistor T which accesses information of word lines, a storage node capacitor C which stores information through bit lines as the access transistor T operates, and a charge-up transistor P which supplies charges to the storage node capacitor, thereby consistently supplying charges to the storage node capacitor, and improving the processing speed of the semiconductor memory device.
In general, a non-volatile semiconductor memory is a semiconductor memory which can continuously maintain the information stored in the memory cell even though power is not supplied.
The non-volatile memory related to the present invention includes memory cells which are configured such that an intermediate layer between a first electrode and a second electrode is an insulating layer or variable resistor.
In the case where the intermediate layer forming the memory cells is an insulating layer, when a breakdown is caused by applying a high voltage for programming to both electrodes, i.e., the first electrode and the second electrode between which the insulating layer is interposed, a resistive path is created, and the insulating layer is changed from an insulating state to a conducting state. The insulating layer becomes an antifuse element.
In this regard, the following definition can be made. If the insulating layer is in the conducting state, programming has been performed and the data ‘0’ is stored. If the insulating layer is in the insulating state, programming has not been performed, and the data ‘1’ is stored.
In the case where the intermediate layer forming the memory cells is a variable resistor, as the variable resistor, a resistance change material or a phase change material can be used.
In the case where the variable resistor forming the memory cells is made of a resistance change material, if a voltage equal to or greater than a set voltage is applied to both electrodes, i.e., the first electrode and the second electrode between which the variable resistor is interposed, the resistance of the variable resistor has a low state. If a voltage equal to or greater than a reset voltage is applied to both electrodes, the resistance of the variable resistor has a high state. It can be defined that the data ‘1’ is stored if the resistance of the variable resistor has a low state, and the data ‘0’ is stored if the resistance of the variable resistor has a high state.
As the resistance change material, various materials such as perowvskite, transition metal oxide, and chalcogenide may be used.
The memory using the resistance change material can be classified into several types depending on the material. Firstly, a material such as a colossal magnetoresistance (CMR) material and Pr1-xCaxMnO3(PCMO) may be inserted between the electrodes, thereby using a change in resistance due to the electric field. Secondly, binary oxide such as Nb2O5, TiO2, NiO and Al2O3 may be fabricated to have a non-stoichiometric composition and used as the resistance change material. Thirdly, as a chalcogenide material, a resistance difference due to a change in the threshold voltage of an Ovonic switch can be used while maintaining an amorphous structure without phase change by flowing a high current as in a phase change RAM (PRAM). Fourthly, the state of the resistance may be changed by doping chromium (Cr) or niobium (Nb) in a ferroelectric material such as SrTiO3 and SrZrO3. Finally, there is a programmable metallization cell (PMC) in which two states of the resistance are formed according to the presence or absence of a conductive channel in a medium due to an electrochemical reaction by doping silver (Ag) having a large ion mobility in a solid electrolyte such as GeSe. Other materials having memory characteristics through stable implementation of two resistor states or processing methods have been reported.
In the case where the variable resistor forming the memory cells is made of a phase change material, it can be defined that the data ‘1’ is stored if the resistance of the phase change material has a low state, and the data ‘0’ is stored if the resistance of the phase change material has a high state.
The phase change material is a material whose phase is changed to a crystalline or amorphous state by a constant current. The crystalline state corresponds to a low resistance state, and the amorphous state corresponds to a high resistance state.
Since memory cells are arranged in rows and columns to form a memory array, a transistor or diode should be included to selectively access the memory cell.
In order to increase the integration density in the current memory devices, a microprocessing technology has been developed such that more memory cells can be integrated in a horizontal structure.
However, the horizontal structure according to the conventional technology has to now depend on the microprocessing technology with physical limits to the integration density.
Thus, there is a need for a new structure capable of easily increasing the integration density instead of the conventional horizontal structure, and a new manufacturing method thereof.